The invention relates to a single handle mixing valve and more particularly with a pusher plate to regulate the mixture ratio and the outflow volume of mixed water.
Known mixer valves of this type consist principally of a base-plate arranged immovably in the valve casing in which apertures are provided for the conducting of hot and cold water and for the discharge of mixed water. A pusher plate, displaced by means of a handle, and provided with an overflow passage, is carried on this base-plate to regulate the mixture and outflow volume. The out-flow volume is set by an upwards or downwards movement of the handle and the mixture ratio by swivelling the handle. Mixing valves of the type described are exemplified in U.S. Pat. Nos. 3,324,884; 3,533,436; and 3,788,354.
One problem common to some prior art mixing valves of the character described is that they exhibit a change in the mixture ratio proportional to or even over-proportional to the swivel angle in the medium range--the so-called comfort range--in which a mixed water with a temperature from approximately 30.degree. to 45.degree. C. should be produced in the fitting. This setting range can only be set relatively inaccurately in the case of the known mixer valves so that precise setting of the outflowing mixed water is practically impossible which is extremely unpleasant particularly in bath and shower systems, etc., because the human body very quickly and easily detects a temperature difference of 1.degree. to 2.degree. C.